Yeah, and the compiler will also report errors if different modules use different versions of the same package. - module A uses v1 and uses trait v1.A - m

Yeah, and the compiler will also report errors if different modules use different versions of the same package. - module A uses v1 and uses trait v1.A - module B uses v2 and uses trait v2.A - will be reported as "A does not implement trait A" It's actually quite discomforting for newcomers.